1. Field of the Invention
This invention relates to novel thioacrylate monomers, polymers of thioacrylates and optical components containing these polymers.
2. Description Relative to the Prior Art
Optical components, such as lenses, prisms, and light guides, are known in the art. It is necessary that materials used for making optical components be colorless and transparent. It is also desirable that these materials have a high refractive index. In the case of lenses, the use of high refractive index materials makes possible the use of thinner lenses having the same focal length as thicker lenses made of materials with a lower refractive index. The use of thinner lenses decreases the volume of space required by the lens within an optical assembly. Also, the manufacture of thinner lenses requires less material, which constitutes a potential savings to the manufacturer.
High refractive index materials have also been shown to be desirable in light guides. U.S. Pat. No. 3,809,686, issued Mar. 19, 1970, describes the method of producing light guides by selectively irradiating polymethyl methacrylate with ultraviolet light at given wavelengths. The selective irradiation causes observable increases in the refractive index of the polymer along the path of the focused radiation. However, the index of refraction of polymethyl methacrylate is only 1.49 to 1.50 and the increases produced by irradiation are relatively small. (The resulting change is refractive index equals 0.5.times.10.sup.-6 E, where E is the exposure in joules per square centimeter for ultraviolet light from a mercury arc.) The use of polymers having a substantially higher refractive index (over 1.60) in optical components would make possible the use of optical components which are considerably thinner than conventionally prepared components. It is thus seen that transparent and colorless polymers of high refractive indices are desirable for use in optical components.